Effect of operating parameters on CO2 capture from biogas with choline chloride—monoethanolamine deep eutectic solvent and its aqueous solution

CO2 capture from biogas is an effective route to facilitate the utilization of biogas by improving its CH4 purity. In this work, choline chloride-monoethanolamine deep eutectic solvent (ChCl-MEA DES), was employed as a promising absorbent for CO2 capture. The effects of absorption pressure and temperature, and water content in DES, on CO2 absorption capacity, rates, and selectivity were experimentally evaluated. The experimental data were analyzed by analysis of variance (ANOVA) and response surface method (RSM). The absorption behavior of CO2 by DES mainly conformed to the laws of physical absorption. The highest CO2 absorption capacity of ChCl-MEA DES was 0.608 mol-CO2/mol-DES, and the best CO2/CH4 selectivity factor was 25. Regression equations of CO2 absorption capacity and rate were established to evaluate the results under different operating conditions.